Table 4: Identified metabolites in the combined and filtered data set. The retention time is measured in minutes and the exact compound mass is stated in Dalton. The columns “Negative” and “Positive” contain the number of associated marker candidates/ions obtained in the negative or positive ionization mode. The column “Ions” contains the sum of associated marker candidates/ions per compound. The column “𝑃 value” contains the minimal adjusted 𝑃 value of the Kruskal-Wallis test over all associated marker candidates, respectively. The column “Mass error” contains the absolute difference between the corrected mass of the marker candidate with the minimal adjusted 𝑃 value and the exact compound mass in Dalton.